The present invention relates to collapsible structures and, more particularly, to collapsible structures with self-locking mechanism and methods of erecting a collapsible structure.
My prior U.S. Pat. Nos. 6,141,934, 5,651,228, 5,444,946, 5,274,980, 5,230,196, RE33,710, 4,970,841, 4,838,003, 4,800,663, 4,761,929, 4,747,239, 4,689,932, 4,666,102, 4,637,180, 4,579,066, 4,561,618, 4,522,008, 4,512,097, 4,473,986, 4,437,275, 4,334,660, 4,290,244, 4,280,521, 4,026,313, and 3,968,808 are incorporated by reference and show various collapsible structures and components therefor. In many collapsible structures of the general type described in these patents, in the course of erecting the structures, the structures must extend beyond the dimensions of the erected shelter. For example, in my U.S. Pat. Nos. 5,444,946 and 5,274,980, in the course of erecting the shelters, they are typically expanded laterally outward significantly past the lateral dimensions of the finished structure. This makes it difficult to provide the structures with a cover as is typically provided on portable shelter type devices. Ordinarily, the covers are attached after erection of the frame of the structure.
Also, because the structures during erection are typically expanded beyond the footprint of the structures in their erected condition, they are generally only secured to the ground or a base after they are finally erected. This can make erection of the structures difficult. For example, in windy conditions, the structures may be blown around. This problem can be exacerbated if there is cover material on the frame because the cover material can act as a sail and make it that much more difficult to erect the structure.
During break down of these structures, the same problems occur as during erection. The covers are ordinarily taken off and the structures are ordinarily disconnected from any ground or base supporting structures before lowering the frame.
It is desirable to provide a collapsible structure that can be erected and broken down without the need to remove a cover from the structure. It is also desirable to provide a structure that can be secured to the ground or a base while the structure is being erected or broken down.
In accordance with one aspect of the present invention, a collapsible structure with a self-locking mechanism includes a first hub, at least two struts pivotably connected at first ends thereof to the first hub and movable relative to each another between a folded position and an expanded position, and a tension member adapted to limit pivotable movement of the at least two struts such that, when in the expanded position, the at least two struts define an angle of less than 180°. The structure further includes a locking hub and at least two locking struts pivotably connected at first ends thereof to the locking hub and, at seconds ends thereof, to connection points on respective ones of the at least two struts.
In accordance with another aspect of the present invention, a method of erecting a collapsible structure includes unfolding a collapsible structure from a folded condition to a collapsed condition. A plurality of base-defining ends of a plurality of end struts of the collapsible structure are fixed in the collapsed condition to points on a surface, the points generally defining a size of a base of the structure in the erected condition. After fixing the base-defining ends to the points on the surface, a center region of the collapsible structure is lifted to an erected height of the collapsible structure. The collapsible structure is locked in an erected condition after lifting the structure to its erected height using an internal locking arrangement of the collapsible structure.